Tulum, Quintana Roo, Mexico. Located in the Mayan Riviera, the archaeological zone of Tulum contains the ruins of a port city built around 1200 AD. It is now a place of high tourist impact with more than 2 million people enjoying the archaeological constructions and the natural landscape that surrounds them. The conservation of the coastal ecosystems has been possible, thanks to the fact that hydro-sedimentary flows have remained in the area, mainly as a result of the limited access of tourists to the beach. If the biophysical components of ecosystems are integrated into the site management decision making processes, natural areas can be appreciated by tourists without irreversible damage being caused. (Photograph taken by Rodolfo Silva Casarín, Instituto de Ingeniería, Universidad Nacional Autónoma de México.)